Process of preparing nitric acid of high concentration.



I 1T0 Drawing,

UT L'EDSTA E PATENT; om 1 MARTIN MOEST, or some, swrrznnnnunnun MoRITz ECKARDT, or 'Hocnsr-oN-THn 7 MAIN, GERMANY, ASSIGNORS 'ro FARBWERKE vomvr. MEISTER LUCIUS ei am'nvmcr, or HGGHST-ON-THE-MAYIN, GERMANY, A CORPORATION OF GERMANY.- v

-PROCESS' OF PREPRIl TG' NITRIC ACID..0F HIGH, CONCENTRATION; I

To all/whom it may concern Be it known that we, MARTIN Mons'r, Ph.-

D., chemist, and Monrrzl'EcKAanr, Ph. D.,

chemist, citizens of the Empire of Germany,

residing at Bodio, Switzerland, and Htichst on-the-Main, Germany, respectively, have inventedcertain new and useful Improve ments :in the Process of Preparing Nitric T Acid of'I-Iigh' Concentration, ofwhich the following is a specification.

Q Hithertohighly concentrated nitric acid Could be produced from dilute nitric acid over 70 per cent. strength without the-aid of dehydrating a'gents; it is impossible, however, to "obtain by this; process acids of higher. concentrations than 7880 per cent.

. Our present invention relates to a.'process by which it'is possible to obtain an acid even ofthehighest concentration without having Ito add-one of the aforesaid agents. This -processcohsists' in boiling nitric acid of a strength greater than that. corresponding 1 with the lowestvapor-pressure, for instance the. nitric acid obtainable by the process described in the said U. '3. Patent No. 1,050,160,

and thus separating'from it the strong acid of lower boiling point, while the dilute acid I of 'higher-b'oiling point is prevented from distilling over.

ratus acting as a dephlegmator, for instance through a fractionating column. In this column a suitable temperature is maintained ,so that the portionsof the acid which boil at a' higher temperature" are' condensed, Whereas the vapors of the strongacid' boiling at a lower temperatlire remain uncondensed and leave the column to be condensed in an ordinary condenser.

It is a'dvantageous to make I co inuoiiby running the acid to be conce "trated ('if'desiredafter being previously- *Warmed) into the column while the boiling ves ed-contains acid of the lowest vapor pressure. The concentrated acid is continuously SpecificationofLettersfatent. npplication' filed mm, 1914. seriaiii s44, 245.

The Process-may, for-instance, be carried the process condensed and collected in the'receiver while ofi'veither directly or after it has been conducted back into the boiling vessel. The.

Patented July 6', 1915. a

.v the weak acidproduced is continuously run whereas the concentration of the remaining acid depends, as usually, on the pressure .prevaihng in-"the apparatus." If the proc- I ess is conducted underfa diminished pressure, the temperature of the column must be lowered accordingly. In order to obtain and maintain the desired temperature of the column, the latter may be heated externally bysurrounding it-with a steam- ]acket orthe necessary'heat may be supplied inside the column, advantageouslyv .by means of nitric acid vapors which are produced inq the boiling-vesseL The heat mg process may alsobe regulated and accel- "erated by warming the acid to be concen-- trated b'efore it flows into the apparatus. The residual nitric acid of the lowest vapor pressure may be re-concentrate'd in the known manner, forinstance by the process' described; in the said U. S. Patent No. 1,050,160 so that, when using Water, nitric oxids and onygen as starting materials, an acid of the highest concentration is obtained;

Having now described our invention, what.

we claim is: v

1. The process of preparing nitric acid of highest concentration, which consists in heating diluted nitric acid the percentage strengthof which is-higher than that of the acid of the lowestvapor-pressure, in the ab sence of any dehydrating agent. causing the vapors to pass through a .fractionating vapors to pass through a fractionating column in which the temperature is kept at a degree corresponding with the desired concentration, and finally condensing the vapors passing over, the residual acid of the lowest vapor-pressure being enriched to a higher column in which the temperature is kept at concentration and subjected again to the foregoing treatment.

3. The process of preparing nitric acid of column is effected by the vapors of the acid of lowest vapor-pressure which is heated in theboiling vessel belonging to the column.

l. The processof preparing nitric acid of highest concentration which consists in conducting diluted nitric acid, the percentage strength of which is higher than that of the Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents acid of the lowest vapor-pressure, in the absence of any dehydrating agent, into a column in which the temperature is kept at a degree corresponding to the desired concentration, and finally condensing the MARTIN MOEST, MORITZ ECKARDT.

lVitnesses JEAN GRUND, CARL GRUND.

Washington, D. 0; 

